Railroad crossing construction

ABSTRACT

Railroad crossing structure for a paved roadway over at least a pair of spaced rails mounted on cross ties to form a railroad track and supported by a ballast comprises a flexible center pad which extends transversely between each pair of spaced rails and flexible side pads which extend transversely between each segment of paved roadway and the rail nearest thereto. The flexible center and side pads are bonded directly to the ballast and comprise a resilient base layer containing a cured flexible thermoset resin and a filler of comminuted scrap rubber, and a resilient wear layer on top of the base layer and containing a cured flexible thermoset resin and a filler of finely divided rubber.

United States Patent Weinberg et al.

RAILROAD CROSSING CONSTRUCTION Assignee: Felt Products Mfg. Co., Skokie,111.

Filed: May 17, 1974 Appl. No.: 470,819

References Cited UNITED STATES PATENTS 1/1947 Abernathy 117/72 X 3/1958Rennels 238/8 2/1963 Spence 238/8 [451 July 15, 1975 Primary ExamznerM.Henson Wood Assistant Examiner-Randolph A. Reese Attorney, Agent. orFirmDressler, Goldsmith, Clement & Gordon, Ltd.

[ 5 7] ABSTRACT Railroad crossing structure for a paved roadway over atleast a pair of spaced rails mounted on cross ties to form a railroadtrack and supported by a ballast comprises a flexible center pad whichextends transversely between each pair of spaced rails and flexible sidepads which extend transversely between each segment of paved roadway andthe rail nearest thereto. The flexible center and side pads are bondeddirectly to the ballast and comprise a resilient base layer containing aCured flexible thermoset resin and a filler of comminuted scrap rubber.and a resilient wear layer on top of the base layer and containing acured flexible thermoset resin and a filler of finely divided rubber.

11 Claims, 5 Drawing Figures emmeemrz a 40 5 Y7 -24 2" an. v-

e-eeaert-ie was if 1391,1610 i l"1A!- RAILROAD CROSSING CONSTRUCTIONBACKGROUND OF THE INVENTION This invention relates to railroad crossingconstruc' tion. More particularly, this invention relates to a flexiblecrossing structure which is bonded directly to the ballast for therailroad track.

Vehicular traffic across railroad tracks is subject to shock, theseverity of which is dependent on the speed and weight of the particularvehicles, but which may cause extensive damage to the suspensions,wheels and tires of the vehicles and thus high maintenance costs due tobroken springs, misaligned front axles which result in unevenly wearingtires, and the like. It is not uncommon for vehicles to slow downsubstantially when approaching a railroad crossing in order to minimizethe passenger discomfort that is experienced during crossing as well asto minimize the likelihood of damage to the vehicle itself. Vehicleshaving relatively small wheels, such as the so-called compact andsubcompact automobiles, receive particularly severe jolts upon crossing.

Moreover, especially heavy jolts are received by small-wheeled utilityvehicles of the type used in industrial operations, e.g., small tractorsand lift trucks having solid rubber tires, which have to negotiatein-plant railroad crossings frequently during daily operations. Thewheels, suspension and frame of such utility vehicles can be damaged anddelicate cargo may be broken or damaged during such crossings.

In addition, the impact on and the vibrations of the track rails due tothe crossing traffic rapidly deteriorate the crossing structure andcause cracks and further roughness in the crossing surface. The lateralimpact of traffic on the rails may shift the rails laterally and maydisturb or displace the track ballast so that the shape of the track atthe crossing assumes an S-shaped configuration. In addition, the impactof traffic on the rails tends to rotate the rails, thereby pulling outthe spikes which secure the rails to the ties, and thus presenting asafety hazard. Water from the roadway surface may seep down into theballast through cracks in crossing surface and along the rails and willtend to further erode the ballast and the roadbed due to a pumpingaction which is experienced when a passing load bears down on the trackabove. That is, a water-and-gravel slurry is formed and is ejectedoutwardly as a weight bears down on the rail. Upon freezing in coldweather such water will also tend to break up the crossing surface.

However, in negotiating a railroad crossing the degree of attention awhich the driver can be expected to devote to the crossing surface isdirectly related to the condition of that surface. If the surface isuneven, or if the driver expects the surface to be uneven, the driverwill undoubtedly attempt to select the smoothest path over the crossing.The attention that the driver devotes to selecting the smoothest pathcould very well reduce the attention given to the observance of trafficsignals or an approaching train. Furthermore, an unexpected encounterwith a rough or uneven railroad crossing surface may cause the driver tolose control of the vehicle and may result in an accident. Thus,continuously providing a reasonably smooth railroad crossing surface isalso important for elimination or reduction of hazards at railroadcrossings.

Several crossing structures have been developed in attempts to alleviatethe foregoing problems. Crossing surfaces of wood fill, asphalt fill,precast concrete panels, reinforced concrete panels, steel-reinforcedrubber panels, and the like, have been used to build a crossing surface.Illustrative of such prior art attempts are U.S. Pat. No. 1,693,878 toWells, U.S. Pat. No. 2,828,079 and U.S. Pat. No. 2,828,080 to Rennels,U.S. Pat. No. 2,950,057 to Speer, and U.S. Pat. No. 3,465,963 to Cailettet al. Yet none of the heretofore proposed crossing structures has beenable to fully overcome the hereinabove mentioned problems at acommercially attractive cost. Many of the prior art structures that havebeen tried under actual service conditions have met with limitedacceptance because of relatively high installation costs or the need forfrequent repair and maintenance, or both.

It is an object of the present invention to provide a new and improvedrailroad crossing structure which is long lasting in service and whichis relatively inexpensive to install and to maintain.

A further object of this invention is to provide a railroad crossingstructure which is resiliently compressible and readily absorbsvibrations, which is less susceptible to damage by the impacts andvibrations normally generated by crossing traffic, and which provides arelatively smooth and safe crossing surface.

Still another object of this invention is to provide a crossingstructure which is resistant to water damage and which substantiallyminimizes water penetration to the underlying track ballast and roadbed.

Yet another object of this invention is to provide a crossing structurewhich does not require spiking or drilling of cross ties forinstallation, which can be installed relatively quickly and with aminimal interference with rail traffic.

Still other objects of the present invention will become apparent to theskilled artisan upon reference to the ensuing specification, theaccompanying drawings, and the claims.

SUMMARY OF THE INVENTION The present invention contemplates a railroadcrossing structure for a paved roadway across at least a pair of spacedrails for guiding railroad vehicles which rails are mounted on cross tiemeans resting on ballast. A flexible center pad means extendstransversely between each pair of spaced rails, is bonded directly tothe ballast and to the rails, and provides a roadway surface between therails. Flexible side pad means extend transversely between each segmentof the paved roadway and the rail nearest thereto, are bonded directlyto the ballast and are in a sealing engagement with the rail nearestthereto, and provide a roadway surface between the paved roadway and theadjacent rail.

Each flexible pad means preferably forms an elastic bond with anadjacent rail and comprises a base layer containing a cured flexiblethermoset resin and a filler of comminuted scrap rubber, and a wearlayer on top of the base layer and containing a cured flexible thermosetresin and a filler of finely divided scrap rubber, the scrap rubberpreferably being formed from worn automobile tires.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings,

FIG. 1 is a plan view of a railroad crossing embodying the presentinvention;

FIG. 2 is a sectional elevation taken along plane 22 in FIG. 1 andenlarged to show interior detail;

FIG. 3 is a sectional elevation taken along plane 3-3 in FIG. 2;

FIG. 4 is a sectional elevation of an embodiment of this invention usingfiller blocks; and

FIG. 5 is a sectional elevation taken along plane 5-5 in FIG. 1 at alocation between two adjacent railroad ties.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, rails and11 are shown in parallel spaced relationship and mounted on a pluralityof cross ties such as cross ties l2 and 13. The cross ties, in turn, areembedded in and rest on ballast 14 in a conventional manner.

The railroad crossing structure of this invention comprises flexiblepads l5, l6 and 17 situated between segments 18 and 19 of a pavedroadway. If desired, expansion joints 20 and 21 can be provided betweenpavement segment 18 and flexible side pad and between pavement segment19 and adjacent flexible side pad 17, respectively. The upper surface offlexible center pad 16 is provided with a suitable groove along bothlongitudinal edges so as to provide flangeways 22 and 23 whichaccommodate the wheel flanges of the railroad equipment.

As shown in FIGS. 2 and 3, a rail, such as rail 10, is mounted on crosstie 24, as by means of a shouldered tie plate 25 and track spikes 26 and27. The resulting assembly rests on ballast 14 which provides thenecessary support for the railroad track. Flexible center pad 16 is castin situ between rails 10 and 11 and extends therebetween. Resilient baselayer 28 is cast from a curable base layer composition which is anadmixture of comminuted scrap rubber with a curable liquid resincomposition. The consistency of the base layer composition is such thata portion of the composition wets cross tie 24 and also ballast 14,preferably flowing at least partially between the individual particlesof ballast l4 and forming a substantially continuous network of liquidinterspersed with air, i.e., in a funicular state. Upon curing of thebase layer 28, the liquid network forms elastic bridges 29 betweenindividual particles of ballast 14 which tend to stabilize and holdballast 14 together, even when subjected to vibrations of water pumping,without adversely affecting its usual function. Moreover, the need forretamping of the ballast after installation is obviated. Alternatively,ballast l4 and cross tie 24 can be pretreated with the curable liquidresin composition alone to pre-wet ballast l4 and to form the desiredliquid network before base layer 28 is cast thereover. If desired, theliquid resin composition can be introduced below each cross tie bydrilling spaced through holes in the tie and pouring the liquid resintherethrough. Preferably, the curable liquid resin composition forms anelastic bond between web 30 and flange 31 of rail 10 on one hand andflexible center pad 16 on the other. At any rate, the produced sealingengagement of the rails by the flexible pad prevents surface water fromseeping downwardly therebetween and also electrically insulates therails from the surroundings. The elastic bond is capable of withstandingthe vibrations generated by the crossing traffic as well as the usualdeflection of the rails when a train passes over.

On top of base layer 28 is provided resilient wear layer 32 which iscast in situ from a wear layer composition which is an admixture offinely-divided rubber in a curable liquid resin composition which can besimilar to or different from the liquid resin composition utilized inbase layer 28 as long as the thermal coefficients of expansion for baselayer 28 and wear layer 32 remain compatible. The flangeways such asflangeway 22 can be conveniently formed during casting by inserting anappropriate form member adjacent to the inside of rail 10 while wearlayer 32 is poured. Upon curing, wear layer 32 provides a smooth roadwaysurface without additional finishing.

Flexible side pads 15 and 17 are of the same construction as flexiblecenter pad 16, and are formed in a similar manner, except that there isno need to form a flangeway along rails 10 and l l. The side padspreferably extend transversely beyond the ends of the cross ties for adistance about equal to the height of the ties. That is, initially baselayers 33 and 42 (FIG. 5) are cast over ballast 14 so as to wet at leasta portion of the individual particles thereof and preferably tointerconnect with base layer 28 below the rails in the regions betweenties in a manner shown in FIG. 5. The cast base layers also wet thecross ties such as cross tie 24 (FIG. 3) and portions of rails 10 and 11(FIGS. 2 and 5). After the base layers have cured, wear layers 34 and 35are cast thereover and permitted to cure. Suitable expansion joints,such as resilient strips 20 and 21 can be provided between flexible sidepad 15 and adjacent pavement segment 18 and between flexible side pad 17and adjacent pavement segment 19, if desired. Preferably the expansionjoints adhere both to the pads and to the pavement segments.

The use of bulk filler materials in the resilient pads of this inventionis illustrated in FIG. 4. Precast concrete slabs 36 and 37 are situatedon cross tie 38 on both sides of rail 10 which is mounted thereon bymeans of shouldered tie plate 39 and track spikes 40 and 41. Base layer33 surrounds slab 36 and sealingly engages one side of flange 31 of rail10. In a similar manner, base layer 28 surrounds slab 37 and sealinglyengages the other side of flange 3]. Elastic bridges 29, in turn, anchorboth base layer 33 and base layer 28 to ballast 14.

The base layer in the flexible crossing pads of this inmention isrelatively thicker but more compressible than the wear layer; however,the relative thicknesses of the two layers are not overly critical.Usually the wear layer is about 0.5 to about 3 inches deep, as measuredfrom the pad surface, and preferably about I inch to about 2 inchesdeep.

The relative amount of comminuted scrap rubber, such as chopped vehicletires or the like, added to the curable liquid resin in the base layercomposition can range from about 2 to about 6 parts by volume of scraprubber to 1 part by volume of the curable resin composition. Preferably,the fillerto-curable resin volume ratio in the base layer is about 4:1to about 6:1, respectively. The particle size of comminuted scrap rubberwhich is used as the filler can vary but should not exceed aboutone-fourth to about three-fourths inch in the longest dimension. Ifdesired, larger filler materials such as concrete filler blocks,aggregate blocks, stone blocks, fiberglass blocks, or the like can alsobe incorporated into the base layer by positioning such filler blocks onthe cross ties, and then pouring the curable liquid resin-fillercomposition thereover.

Finely-divided rubber particles having a particle size range of about to300 mesh are utilized as filler in the wear layer. Fine rubber buffingsor finely-ground rubber from old tires and substantially free from tirecord particles are especially desirable filler materials for thispurpose. The volume ratio of filler-to-curable resin in the wear layercan be about 1:] to about 4:1, respectively. Preferably the volume ratiois about 3:l, respectively.

For preparing the base and wear layers having the desired physicalproperties suitable are glycidyl ether resins cured to a flexible stateand preferably having a tensile elongation of at least about 5 percentat break point. Typical of such resins are diglycidyl ether of bisphenolA, diglycidyl ether of bisphenol F, the glycidyl ethers of glycerol,epoxylated novolacs, and the like, which are derived fromepichlorohydrin and a polyhydric material such as polynuclearpolyhydroxy phenol, e.g., bisphenol A, bisphenol F, trihydroxyl diphenyldimethyl methane, 4,4'-dihydroxy biphenyl, and the like, a polyol, e.g.,ethylene glycol, 2,3-butane diol, erythritol, glycerol, and the like, anovolac resin and similar materials. The aforementioned curable epoxyresins can be polymerized through the hydroxyl groups in the presence ofsuitable catalysts such as tertiary amines, inorganic bases, or thelike, or the resin chains bearing the oxirane group can be joined by areactive intermediate such as a polyfunctional primary amine or apolyfunctional secondary amine, i.e., cured, to produce a flexiblethermoset resin. Other suitable curing agents for this purpose areorganic acids and acid anhydrides, BF; monoethylamine, and the like.

These epoxy resins can be used as the sole ingredient in the liquidcurable composition, or resinous modifiers or flexibilizers can becombined therewith. Suitable modifiers are polyepoxides such asdiglycidyl ether, butadiene dioxide, glycerol-based epoxy resins,alkylglycidyl ethers, phenylglycidyl ether, and the like. Suitableflexibilizers also are thiol-terminated polysulfides which can beconveniently prepared by condensing organic polyhalides with inorganicpolysulfides, the relatively higher molecular weight diisocyanates,e.g., a reaction product of tolylene diisocyanate and polybutane diol,the thermoplastic polyamide resins, polyether polythiols and the like,which will react with the epoxy resin chain and will impart flexibilityto the resulting thermoset resin.

For forming the base layer in the railroad crossing pads of thisinvention a particularly preferred elastomer is the condensation productof diglycidyl ether of bisphenol A and an ethyl formal disulfide polymerof the general formula wherein n is of sufficient magnitude to providean average molecular weight of about 400 to about 1200. The weight ratioof diglycidyl ether resin to polysulfide polymer in the cured elastomercan range from about 5:1 to about [:2. Preferably, about 3 parts byweight of the diglycidyl ether resin per 1 part by weight of thepolysulfide polymer are used. Suitable catalysts or curing agents forproducing the foregoing diglycidyl ether resin-polysulfide resincondensation product are the dialkylaminoalkyl phenols such asdimethylaminomethyl phenol, 2,4,6- tri(dimethylaminomethyl) phenol, andthe like, which can be present in an amount of about 0.7 to about 0.4parts by weight.

For the wear layer, a particularly preferred elastomer is a condensationproduct of diglycidyl ether of bisphenol A with a low-viscosity,flexibilizing polyepoxide resin such as an aliphatic polyglycidyl ethercommercially available from Celanese Coatings Co. under the designationEPl-REZ 505 and having an equivalent weight per epoxide of about550-650, and viscosity at 77F. of about 300-400 cps, cured with analiphatic amine such as a phenolic accelerated aliphatic polyaminecommercially available from Celanese Coatings Co. under the designationEPl-CURE 874 and having an approximate equivalent weight of about 31 andviscosity at 77F. of about l00-200 cps. The diglycidyl ether resin andthe flexibilizing polyepoxide resin in the cured elastomer can bepresent in a weight ratio of about 2:1 to about l:4, respectively.Preferably, about 0.75 parts by weight of the diglycidyl ether resin per1 part by weight of the polyepoxide resin are used. Optionally, up toabout 2.5 weight percent carbon black, based on the weight of thecurable wear layer composition, can be added as a colorant for the wearlayer. In lieu of the polyepoxide resin, a copolymerizable resin such asa diglycidyl ether of an aliphatic alcohol, and the like can be used, ifdesired. Suitable curing agents for the wear layer are aliphatic aminesor polyamines, amideamine adducts, dimercaptans, aromatic amines, andthe like, in an amount of about 0.5 to about 0.9 parts by weight.

Another suitable curable resin for forming the wear layer and havinggood abrasion resistance is a flexible polyurethane resin made byreacting an organic polyisocyanate with a polyol in a manner well knownin the art.

The railroad crossing structure of this invention can be convenientlymanufactured in situ be cleaning out any existing pavement as well assome ballast down to about cross tie level or slightly below in theregion between the rails, and outwardly from the rails for a distance ofabout l8 to about 24 inches. If desired, all of the old ballast can beremoved in the crossing area and replaced with clean, new ballast.

A curable base layer composition is then prepared from a selectedpolymerizable liquid composition by admixing therewith comminuted scraprubber to form a castable slurry having a desired consistency. If theresulting curable base layer composition is relatively viscous,preferably the cleaned out crossing region, including the filler blocks,is prc-wetted with a polymerizable liquid composition.

Next the curable base layer composition is deposited into the cleanedout region between the rails and between the adjacent pavement segment(or an expansion joint abutting the pavement segment) and the railnearest thereto, and is tamped into place to completely fill all voidspace up to a level about 2 to 3 inches below roadway surface.

Depending on what portion of the rail web is covered by the base layerwhen poured in place, a temporary form for providing a flangeway alongthe inside of the rails may or may not be needed while the base layer ispoured. in any event, a flangeway form is provided ad jacent the insideof each of the rails when the wear layer is poured in place.

A curable wear layer composition prepared from a selected polymerizableliquid composition and a finelydivided rubber filler is then poured overthe base layer. The wear layer composition usually has a higher resincontent than the underlying base layer composition and is more fluid soas to provide good wetting and ultimate adhesion between the base layerand the wear layer and also between the rails and the wear layer. Thewear layer composition is poured to the level of the rails themselvesand is brought over contiguous to the rails on the outside and over tothe removable flangeway forms in the region between the rails.Thereafter the poured wear layer is tamped down on top of the base layerand permitted to cure so as to provide a smooth, finished roadwaysurface.

The base layer and the wear layer usually cure to an extent sufficientto bear traffic within about 4 to about 6 hours, depending on the curingagent that is employed and also, of course, on the ambient temperature.If a faster cure rate is desired, the curable compositions can be heatedbefore pouring.

A railroad crossing has been built in accordance with the presentinvention, and has satisfactorily withstood one winter season at belowfreezing temperatures while subjected to daily train and vehiculartraffic. The flexible center pad and the flexible side pads were about 6inches thick, having a flexible base layer thickness of about 4 inchesand a flexible wear layer thickness of about 2 inches.

The curable liquid resin formulation for the base layer was made up ofabout parts by weight diglycidyl ether of bisphenol A, about 2 parts byweight ethyl formal disulfide polymer having a molecular weight of about1000, and about 0.5 parts by weight 2,4,6- tri(dimethylaminomethyl)phenol. Comminuted scrap rubber from automobile tires and havingparticles ranging in size from about one-fourth inch to aboutthreefourths inch in the longest dimension thereof was admixed with thecurable liquid resin formulation to form a slurry having afiller-to-curable resin volume ratio of about 4:1.

Concrete slabs measuring about 24 X 16 X 4 inches were utilized as aninorganic filler, and were positioned at a transverse spacing of about 8to 12 inches between adjacent slabs and a longitudinal spacing of about1 inch between adjacent slabs.

An aliquot of the curable liquid resin formulation was used to wet theballast, the cross ties, and the concrete slabs at the railroad crossingin a region from which old pavement and some ballast had been previouslyremoved to a level of about the top surface of the cross ties supportingthe rails. Thereafter, the slurry for the base layer was poured into thecleaned-out region and leveled off about 3 inches from the pavementsurface. Care was taken that the slurry was in intimate contact with therails, the cross ties, and the supporting ballast.

Thereafter a curable liquid resin formulation for the wear layer wasprepared containing about 1.65 parts by weight diglycidyl ether ofbisphenol A, about 2.15 parts by weight polyepoxide resin prepared froma polyhydric alcohol and having an approximate weight per epoxide ofabout 600, and about 0.8 parts by weight of phenolic acceleratedaliphatic amine. Additionally about 0.15 parts by weight of carbon blackwas stirred into the curable wear layer formulation as a colorant andenough finely-divided rubber buffings were added to the formulation togive a slurry having a filler-to curable resin volume ratio of about3:1.

Flangeway forms were then placed along the inside of the rails at thecrossing, and the obtained slurry was cast over the base layer alreadyin place and tamped down about level with the pavement surface and therails. Surface of the wear layer was smoothed out and finished, and thecast pads were permitted to cure at ambient temperature for about 4hours. After this time period the flangeway forms were removed, and therailroad crossing was placed in service and periodically examined. Theside pads and the center pad were observed to flex when a heavy loadpassed thereover, but after about 8 months of use no deterioration ofthe pad surface is apparent.

The foregoing specification and the drawing are intended as illustrativeand are not to be taken as limiting. Still other variations andmodifications are possible without departing from the spirit and scopeof this invention.

What is claimed is:

l. A railroad crossing structure for a paved roadway across at least apair of spaced rails for guiding railroad vehicles and mounted on crosstie means supported on ballast which comprises a flexible center padmeans extending transversely between each pair of spaced rails,providing a roadway surface therebetween, and being bonded directly tosaid ballast and being in a sealing engagement with said rails; and

a flexible side pad means extending transversely between each pavementsegment and the rail nearest thereto, providing a roadway surfacetherebetween, and being bonded directly to said ballast and being in asealing engagement with said nearest rail;

each of said flexible pad means having a base layer comprising aflexible thermoset resin which is a cured glycidyl ether resin,comminuted scrap rubber, and an inorganic bulk filler, and a wear layerof a cured flexible thermoset resin and finelydivided scrap rubber ontop of said base layer, scrap rubber-to-cured resin volume ratio in saidbase layer being about 2:1 to about 6:1 and scrap rubber-to-cured resinvolume ratio in said wear layer being about 1:1 to about 4:1; and saidcured glycidyl ether resin in said base layer bonding togetherindividual ballast particles below said base layer and bonding said baselayer to said ballast.

2. The railroad crossing structure in accordance with claim 1 whereinsaid flexible pad means further include an elastic bridge network ofsaid cured glycidyl ether resin holding together individual particles ofsaid ballast.

3. The railroad crossing structure in accordance with claim 1 whereinsaid inorganic bulk filler is a plurality of blocks.

4. A railroad crossing structure for a paved roadway across at least apair of spaced rails for guiding railroad vehicles and mounted on crosstie means supported on ballast which comprises a flexible center padmeans extending transversely between each pair of spaced rails,providing a roadway surface therebetween, and being bonded directly tosaid ballast and being in a sealing engagement with said rails; and

a flexible side pad means extending transversely between each pavementsegment and the rail nearest thereto, providing a roadway surfacetherebetween, and being bonded directly to said ballast and being in asealing engagement with said nearest rail;

each of said flexible pad means comprising a base layer of a curedflexible thermoset resin which is a condensation product of a glycidylether resin and a thiol-terminated polysulfide resin and a filler whichis comminuted scrap rubber, and a wear layer of a cured flexiblethermoset resin which is an aliphatic amine-cured glycidyl ether resinand a filler which is finely-divided scrap rubber on top of said baselayer, a filler-to-cured resin volume ratio in said base layer beingabout 2:1 to about 6:1, and the tiller-to-cured resin volume ratio insaid wear layer being about 1:1 to about 4:1.

5. The railroad crossing structure in accordance with claim 4 whereinsaid flexible thermoset resin in the base layer is a condensationproduct of diglycidyl ether of bisphenol A and ethyl formal disulfldepolymer in a weight ratio of about 5:1 to about 122, respectively, theethyl formal disulflde polymer having the general formula where g is ofsufficient magnitude to give a molecular weight of about 400 to about1200, and about 0.7 to about 0.4 parts by weight 2,4,6-tri(dimethylaminomethyl) phenol; and wherein said flexible thermosetresin in the wear layer comprises a diglycidyl ether of bisphenol A anda flexibilizing polyepoxide in a weight ratio of about 2:1 to about 1:4,respectively, and about 0.5 to about 0.9 parts by weight of an aliphaticpolyamine curing agent.

6. A method for manufacturing a resilient railroad crossing pad toprovide a crossing structure across at least a pair of spaced railsmounted on cross tie means supported on ballast which comprises thesteps of preparing a curable base layer composition comprising aglycidyl ether resin and a thiol-terminating polysulfide resin, adialkylaminoalkyl phenol curing agent, and a particulate resilientfiller; said filler and said resin being present in said curable baselayer composition in a volume ratio of about 4:1 to about 6:1,respectively; casting said curable base layer composition over saidballast to form a base layer for said pad 1L1 it u;

curing the cast base layer so as to form a condensation product of saidglycidyl ether and said polysultide;

preparing a curable wear layer composition comprising a glycidyl etherresin, a polyepoxide resin, an aliphatic amine cross-linking agent, anda particulate resilient filler; said filler and said resin being presentin said second curable composition in a volume ratio of about 3:1,respectively;

casting said curable wear layer composition to form a wear layer on topof said base layer; and

curing the cast wear layer so as to form an aliphatic amine-curedglycidyl ether polymer.

7. The method in accordance with claim 6 wherein the curable liquidresin for the base layer composition is a mixture of glycidyl etherresin and thiol-terminated polysulfide in a weight ratio of about 5:1 toabout 1:2, respectively, and about 0.7 to about 0.4 parts by weightdialkylaminoalkyl phenol, and wherein the curable liquid resin for thewear layer composition is a mixture of glycidyl ether resin and aflexibilizing polyepoxide in a weight ratio of about 2:1 to about 1 :4,respectively, and wherein about 0.5 parts to about 0.9 parts by weightof an aliphatic amine curing agent are present in the mixture.

8. The method in accordance with claim 6 wherein the curable liquidresin for the base layer composition contains about 5 parts by weightdiglycidyl ether of bisphenol A, about 2 parts by weight ethyl formaldisulfide polymer of the general formula where n is of sufficientmagnitude to give a molecular weight of about 1000, about 0.5 parts byweight 2,4,6- tri(dimethylaminomethyl) phenol; and wherein the curableliquid resin for the wear layer composition contains about 1.65 parts byweight diglycidyl ether of bisphenol A, about 2.15 parts by weight of aflexibilizing polyepoxide, and about 0.8 parts by weight aliphaticpolyamine.

9. The method in accordance with claim 6 wherein that portion of theballast which is covered by said crossing pad is pre-wetted with acurable liquid resin composition before said curable base layercomposition is cast thereover.

10. A method of repairing an existing paved roadway crossing over arailroad track which includes a pair of spaced rails supported on tiessupported by a ballast material and wherein roadway pavement extends upto and transversely between the rails, which comprises cleaning outexisting pavement and a portion of said ballast down to at least tielevel in the region between said rails and also in a region immediatelyadjacent to each pair of spaced rails;

casting a base layer comprising a curable liquid resin composition and afiller of comminuted scrap rubber in said cleaned out regions to a levelabove the tie level but below the pavement level;

curing the cast base layer so as to produce a flexible base;

casting a wear layer comprising a curable liquid resin mixture and afiller of finely-divided scrap rubber substantially level with saidrails and said pavement; and

curing the cast wear layer so as to produce a flexible wear layer oversaid flexible base;

the filler-to-curable resin volume ratio in the base layer being about2:1 to about 6:1, respectively, and the filler-to-curable resin volumeratio in the wear layer being about 1:1 to about 4:1, respectively.

l 1. The method in accordance with claim 10 wherein thefiller-to-curable resin volume ratio in the base layer is about 4:1 toabout 6:1 and the filler-to-curable resin volume ratio in the wear layeris about 3:1.

1. A RAILROAD CROSSING STRUCTURE FOR A PAVED ROADWAY ACROSS AT LEAST APAIR OF SPACED RAILS FOR GUIDING RAILROAD VEHICLES AND MOUNTED ON CROSSTIE MEANS SUPPORTED ON BALLAST WHICH COMPRISES A FLEXIBLE CENTER PADMEANS EXTENDING TRANSVERSELY BETWEEN EACH PAIR OF SPACED RAILS,PROVIDING A ROADWAY SURFACE THEREBETWEEN, AND BEING BONDED DIRECTLY TOSAID BALLAST AND BEING IN A SEALING ENGAGEMENT WITH SAID RAILS, AND AFLEXIBLE SIDE PAD MEANS EXTENDING TRANSVERSELY BETWEEN EACH PAVEMENTSEGMENT AND THE RAIL NEAREST THERETO, PROVIDING A ROADWAY SURFACETHEREBETWEEN, AND BEING BONDED DIRECTLY TO SAID BALLAST AND BEING IN ASEALING ENGAGEMENT WITH SAID NEAREST RAIL, EACH OF SAID FLEXIBLE PADMEANS HAVING A BASE LAYER COMPRISING A FLEXIBLE THERMOSET RESIN WHICH ISA CURED GLYCIDYL ETHER RESIN, COMMINUTED SCRAP RUBBER, AND AN INORGANICBULK FILLER, AND A WEAR LAYER OF A CURED FLEXI LE THERMOSET RESIN ANDFINELY-DIVIDED SCRAP RUBBER ON TOP OF SAID BASE LAYER, SCRAPRUBBER-TO-CURED RESIN VOLUME RATIO IN SAID BASE LAYER BEING ABOUT 2:1 TOABOUT 6:1 AND SCRAP RUBBERTO-CURED RESIN VOLUME RATIO IN SAID WEAR LAYERBEING ABOUT 1:1 TO ABOUT 4:1, AND SAID CURED GLYCIDYL ETHER RESIN INSAID BASE LAYER BONDING TOGETHER INDIVIDUAL BALLAST PARTICLES BELOW SAIDBASE LAYER AND BONDING SAID BASE LAYER TO SAID BALLAST.
 2. The railroadcrossing structure in accordance with claim 1 wherein said flexible padmeans further include an elastic bridge network of said cured glycidylether resin holding together individual particles of said ballast. 3.The railroad crossing structure in accordance with claim 1 wherein saidinorganic bulk filler is a plurality of blocks.
 4. A railroad crossingstructure for a paved roadway across at least a pair of spaced rails forguiding railroad vehicles and mounted on cross tie means supported onballast which comprises a flexible center pad means extendingtransversely between each pair of spaced rails, providing a roadwaysurface therebetween, and being bonded directly to said ballast andbeing in a sealing engagement with said rails; and a flexible side padmeans extending transversely between each pavement segment and the railnearest thereto, providing a roadway surface therebetween, and beingbonded directly to said ballast and being in a sealing engagement withsaid nearest rail; each of said flexible pad means comprising a baselayer of a cured flexible thermoset resin which is a condensationproduct of a glycidyl ether resin and a thiol-terminated polysulfideresin and a filler which is comminuted scrap rubber, and a wear layer ofa cured flexible thermoset resin which is an aliphatic amine-curedglycidyl ether resin and a filler which is finely-divided scrap rubberon top of said base layer, a filler-to-cured resin volume ratio in saidbase layer being about 2:1 to about 6:1, and the filler-to-cured resinvolume ratio in said wear layer being about 1:1 to about 4:1.
 5. Therailroad crossing structure in accordance with claim 4 wherein saidflexible thermoset resin in the base layer is a condensation product ofdiglycidyl ether of bisphenol A and ethyl formal disulfide polymer in aweight ratio of about 5:1 to about 1:2, respectively, the ethyl formaldisulfide polymer having the general formula H ( SCH2CH2OCH2OCH2CH2S )nHwhere n is of sufficient magnitude to give a molecular weight of about400 to about 1200, and about 0.7 to about 0.4 parts by weight2,4,6-tri(dimethylaminomethyl) phenol; and wherein said flexiblethermoset resin in the wear layer comprises a diglycidyl ether ofbisphenol A and a flexibilizing polyepoxide in a weight ratio of about2:1 to about 1:4, respectively, and about 0.5 to about 0.9 parts byweight of an aliphatic polyamine curing agent.
 6. A method formanufacturing a resilient railroad crossing pad to provide a crossingstructure across at least a pair of spaced rails mounted on cross tiemeans supported on ballast which comprises the steps of preparing acurable base layer composition comprising a glycidyl ether resin and athiol-terminating polysulfide resin, a dialkylaminoalkyl phenol curingagent, and a particulate resilient filler; said filler and said resinbeing present in said curable base layer composition in a volume ratioof about 4:1 to about 6:1, respectively; casting said curable base layercomposition over said ballast to form a base layer for said pad in situ;curing the cast base layer so as to form a condensation product of saidglycidyl ether and said polysulfide; preparing a curable wear layercomposition comprising a glycidyl ether resin, a polyepoxide resin, analiphatic amine cross-linking agent, and a particulate resilient filler;said filler and said resin being present in said second curablecomposition in a volume ratio of about 3:1, respectively; casting saidcurable wear layer composition to form a wear layer on top of said baselayer; and curing the cast wear layer so as to form an aliphaticamine-cured glycidyl ether polymer.
 7. The method in accordance withclaim 6 wherein the curable liquid resin for the base layer compositionis a mixture of glycidyl etHer resin and thiol-terminated polysulfide ina weight ratio of about 5:1 to about 1:2, respectively, and about 0.7 toabout 0.4 parts by weight dialkylaminoalkyl phenol, and wherein thecurable liquid resin for the wear layer composition is a mixture ofglycidyl ether resin and a flexibilizing polyepoxide in a weight ratioof about 2:1 to about 1:4, respectively, and wherein about 0.5 parts toabout 0.9 parts by weight of an aliphatic amine curing agent are presentin the mixture.
 8. The method in accordance with claim 6 wherein thecurable liquid resin for the base layer composition contains about 5parts by weight diglycidyl ether of bisphenol A, about 2 parts by weightethyl formal disulfide polymer of the general formula H (SCH2CH2OCH2OCH2CH2S )nH where n is of sufficient magnitude to give amolecular weight of about 1000, about 0.5 parts by weight2,4,6-tri(dimethylaminomethyl) phenol; and wherein the curable liquidresin for the wear layer composition contains about 1.65 parts by weightdiglycidyl ether of bisphenol A, about 2.15 parts by weight of aflexibilizing polyepoxide, and about 0.8 parts by weight aliphaticpolyamine.
 9. The method in accordance with claim 6 wherein that portionof the ballast which is covered by said crossing pad is pre-wetted witha curable liquid resin composition before said curable base layercomposition is cast thereover.
 10. A method of repairing an existingpaved roadway crossing over a railroad track which includes a pair ofspaced rails supported on ties supported by a ballast material andwherein roadway pavement extends up to and transversely between therails, which comprises cleaning out existing pavement and a portion ofsaid ballast down to at least tie level in the region between said railsand also in a region immediately adjacent to each pair of spaced rails;casting a base layer comprising a curable liquid resin composition and afiller of comminuted scrap rubber in said cleaned out regions to a levelabove the tie level but below the pavement level; curing the cast baselayer so as to produce a flexible base; casting a wear layer comprisinga curable liquid resin mixture and a filler of finely-divided scraprubber substantially level with said rails and said pavement; and curingthe cast wear layer so as to produce a flexible wear layer over saidflexible base; the filler-to-curable resin volume ratio in the baselayer being about 2:1 to about 6:1, respectively, and thefiller-to-curable resin volume ratio in the wear layer being about 1:1to about 4:1, respectively.
 11. The method in accordance with claim 10wherein the filler-to-curable resin volume ratio in the base layer isabout 4:1 to about 6:1 and the filler-to-curable resin volume ratio inthe wear layer is about 3:1.